Magnetometer Raw Data

This data products contains daily .zip files from 3 magnetometers. These files are primarily to facilitate file transfer to the Royal Meteorological Institute of Belgium researchers. The content of the .zip files varies depending on the magnetometer. 

Both the RMI GyroDIF Automatic Magnetometer MK3 and the RMI GyroDIF Automatic Magnetometer MK3 are used to calibrate the LEMI Vector Analog Magnetometer LEMI-039 data.

GEM Systems GSM-90 Overhauser Scalar Magnetometer

The .zip files from this device include two files within it. These files are .csv format with two different sample rates of 12 samples per minute (1 sample every 5 second) and 1 sample per minute. The structure of these .csv files is as follows: 

1m data lines

2022 10 02 00 00 00 2022 10 02 00 00 00 48858.43 99 88888.00
2022 10 02 00 01 00 2022 10 02 00 01 00 48858.39 99 88888.00

Each column is detailed below: 

Columns1-3Columns 4-6Columns 7-9Column 10-12Column 13Column 14Column 15
YYYY-MM-DDHH-MM-SSHH-MM-SSAbsolute Magnetic field magnitude in nT (F)

Quality indicator (Q) coefficient XY, where:

  • X is associated with measurement time and is a sort of gradient indicator.
    • 9 means max measurement time was accomplished.
    • 0 means measurement was too short.
  • Y represents the area under signal amplitude coincident with the time of measurement.
    • 9 means optimal conditions
    • 0 means unacceptable reading.
  • X=0 causes Y=0 but not vice versa.
delta time between capturing of data and receiving it on the Linux beaglebone (internal computer of the Mini Junction Box powering the magnetometers)always 88888.00, not applicable for 1 minute data

5s data lines

2022 09 11 00 00 00 48859.55 99 3.03
2022 09 11 00 00 05 48859.56 99 3.04

Each column is detailed below: 

Columns 1-3Columns 4-6Column 7Column 8Column 9
YYYY-MM-DDHH-MM-SSAbsolute Magnetic field magnitude in nT (F)

Quality indicator (Q) coefficient XY, where:

  • X is associated with measurement time and is a sort of gradient indicator.
    • 9 means max measurement time was accomplished.
    • 0 means measurement was too short.
  • Y represents the area under signal amplitude coincident with the time of measurement.
    • 9 means optimal conditions
    • 0 means unacceptable reading.
  • X=0 causes Y=0 but not vice versa.
delta time between capturing of data and receiving it on the Linux beaglebone (internal computer of the Mini Junction Box powering the magnetometers)

RMI GyroDIF Automatic Magnetometer MK3

The .zip files from this device include 4 sub-folders, namely:

/calc,

/debug,

/gyro, and

/spot.

All files are tab separated and end with CR LF. In all files, angles are in decimal degrees and timestamps in UTC.

The magnetic results are located in the directory /calc. Each day a new file is made and placed in the directory calc/YYYY/MM/yyyymmdd.calc. The header of the file contains a summary of the station.

Column 1Column 2Column 3Column 4
Various fields, such as 'RECTIME', 'RECLUE", etcYYYY-MM-DDHH:MM:SS

Declination measurements and inclination measurements.

The four declination measurements to be executed are :

  • DECLUE : Declination measurement towards the East with Fluxgate Probe UP
  • DECLDW : Declination measurement towards the West with Fluxgate Probe DOWN
  • DECLDE : Declination measurement towards the East with Fluxgate Probe DOWN
  • DECLUW : Declination measurement towards the West with Fluxgate Probe UP
If a declination program is executed successfully it will store an in memory declination result that contains :
  • Four successful declination measurements (one for each of the above described positions).
  • The magnetic meridian.
  • The possibility to calculate the current measured declination with a timestamp that equals the mean value of the
  • four timestamps of the declination measurements.

Inclination program is similar to the declination program except that it is executed in the levelled vertical circle at the magnetic meridian. The inclination program has always as prerequisite a successful declination program execution.
The inclination program has as task to do four successful inclination measurements. A single inclination measurement
is successful if it contains two successive non-saturated fluxgate measurements in one specific direction. The four
measurements to be executed are:

  • INCLUN : Inclination measurement towards the North with Fluxgate Probe UP
  • INCLDS : Inclination measurement towards the South with Fluxgate Probe DOWN
  • INCLDN : Inclination measurement towards the North with Fluxgate Probe DOWN
  • INCLUS : Inclination measurement towards the South with Fluxgate Probe UP

If an inclination program is executed successfully it will store an in memory inclination result that contains :

  • Four successful inclination measurements (one for each of the above described positions).
  • The possibility to calculate the current measured inclination with a timestamp that equals the mean value of the
    four timestamps of the inclination measurements.

As a GyroDIF can operate quickly, it is possible to calculate the approximate real declination and inclination with timestamp the mean value of the 4 timestamps of the corresponding measurement.
You can find the spot value files in the subdirectory /spot. Each day a new file is made and placed in the directory spot/YYYY/MM/yyyymmdd.spot. The content of a spot value file contains declination and inclination with timestamp. The trace is also noted. The trace is the azimuth of the 0 of the levelled horizontal circle. The trace is taken from the Gyro results.

Columns 1-3Columns 4-6Column 7Column 8Column 9Column 9Column 10
YYYY-MM-DDHH-MM-SSTraceDeclination  InclinationDecTime

 IncTime

The gyroscope results are located in the directory /gyro. Each day a new file is made and placed in the directory gyro/YYYY/MM/yyyymmdd.calc. It contains the latest calculated trace and the updated Kalman filtered trace.

Columns 1-3Columns 4-6Column 7Column 8
YYYY-MM-DDHH-MM-SS trace (deg) filtered (deg) 

The debug files all end with .raw they are available in the /debug directory. The gyro measurements have debug files and saved as debug/gyro/YYYY/MM/yyyymmdd.raw. They are only useful for the autoDIF team to verify the correctness of the calculated results. 

LEMI Vector Analog Magnetometer LEMI-039

The files from the above two devices are used to correct readings from LEMI which is Seabed Magnetometer (SBM). Same as the above two devices, the format of archived files are .zip files. The raw data has .csv format where UTC time, magnetic field component values in nT, temperature of electronic components, Angle AX, Angle AY, and voltage are recorded. The content of .zip and .csv files is yet to be clarified further. The files from this instrument are subject to diversion, so the files may not be immediately available to users.

Oceans 3.0 API filter: dataProductCode=RAWMAG

Revision History

  • 2022-11-25: Data product initially released

Data Product Options

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Formats

This format is a .zip 

Oceans 3.0 API filter: extension=ZIP

Examples

GEM Systems GSM-90 Overhauser Scalar Magnetometer

RMI GyroDIF Automatic Magnetometer MK3

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